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XInTheDark
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VVLTC search tune
Tuned with 85k games at VVLTC. VVLTC 1st sprt: https://tests.stockfishchess.org/tests/view/6648b836308cceea45533ad7 LLR: 2.94 (-2.94,2.94) <0.00,2.00> Total: 14880 W: 3890 L: 3652 D: 7338 Ptnml(0-2): 0, 1255, 4694, 1489, 2 VVLTC 2nd sprt: https://tests.stockfishchess.org/tests/view/6648c34f308cceea45533b4f LLR: 2.95 (-2.94,2.94) <0.50,2.50> Total: 24984 W: 6502 L: 6235 D: 12247 Ptnml(0-2): 1, 2178, 7867, 2445, 1 closes #5264 Bench: 1198142
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‎src/search.cpp‎

Lines changed: 42 additions & 42 deletions
Original file line numberDiff line numberDiff line change
@@ -59,9 +59,9 @@ static constexpr double EvalLevel[10] = {0.981, 0.956, 0.895, 0.949, 0.913,
5959

6060
// Futility margin
6161
Value futility_margin(Depth d, bool noTtCutNode, bool improving, bool oppWorsening) {
62-
Value futilityMult = 131 - 48 * noTtCutNode;
63-
Value improvingDeduction = 2 * improving * futilityMult;
64-
Value worseningDeduction = 330 * oppWorsening * futilityMult / 1024;
62+
Value futilityMult = 127 - 48 * noTtCutNode;
63+
Value improvingDeduction = 65 * improving * futilityMult / 32;
64+
Value worseningDeduction = 334 * oppWorsening * futilityMult / 1024;
6565

6666
return futilityMult * d - improvingDeduction - worseningDeduction;
6767
}
@@ -73,15 +73,15 @@ constexpr int futility_move_count(bool improving, Depth depth) {
7373
// Add correctionHistory value to raw staticEval and guarantee evaluation does not hit the tablebase range
7474
Value to_corrected_static_eval(Value v, const Worker& w, const Position& pos) {
7575
auto cv = w.correctionHistory[pos.side_to_move()][pawn_structure_index<Correction>(pos)];
76-
v += cv * std::abs(cv) / 7179;
76+
v += cv * std::abs(cv) / 6047;
7777
return std::clamp(v, VALUE_TB_LOSS_IN_MAX_PLY + 1, VALUE_TB_WIN_IN_MAX_PLY - 1);
7878
}
7979

8080
// History and stats update bonus, based on depth
81-
int stat_bonus(Depth d) { return std::clamp(200 * d - 280, 16, 1495); }
81+
int stat_bonus(Depth d) { return std::clamp(187 * d - 288, 17, 1548); }
8282

8383
// History and stats update malus, based on depth
84-
int stat_malus(Depth d) { return (d < 4 ? 586 * d - 284 : 1639); }
84+
int stat_malus(Depth d) { return (d < 4 ? 630 * d - 281 : 1741); }
8585

8686
// Add a small random component to draw evaluations to avoid 3-fold blindness
8787
Value value_draw(size_t nodes) { return VALUE_DRAW - 1 + Value(nodes & 0x2); }
@@ -311,12 +311,12 @@ void Search::Worker::iterative_deepening() {
311311

312312
// Reset aspiration window starting size
313313
Value avg = rootMoves[pvIdx].averageScore;
314-
delta = 10 + avg * avg / 9474;
314+
delta = 10 + avg * avg / 9828;
315315
alpha = std::max(avg - delta, -VALUE_INFINITE);
316316
beta = std::min(avg + delta, VALUE_INFINITE);
317317

318318
// Adjust optimism based on root move's averageScore (~4 Elo)
319-
optimism[us] = 117 * avg / (std::abs(avg) + 88);
319+
optimism[us] = 116 * avg / (std::abs(avg) + 84);
320320
optimism[~us] = -optimism[us];
321321

322322
// Start with a small aspiration window and, in the case of a fail
@@ -503,10 +503,10 @@ void Search::Worker::clear() {
503503
for (StatsType c : {NoCaptures, Captures})
504504
for (auto& to : continuationHistory[inCheck][c])
505505
for (auto& h : to)
506-
h->fill(-62);
506+
h->fill(-60);
507507

508508
for (size_t i = 1; i < reductions.size(); ++i)
509-
reductions[i] = int((21.19 + std::log(size_t(options["Threads"])) / 2) * std::log(i));
509+
reductions[i] = int((21.69 + std::log(size_t(options["Threads"])) / 2) * std::log(i));
510510

511511
refreshTable.clear(networks);
512512
}
@@ -739,7 +739,7 @@ Value Search::Worker::search(
739739
// Use static evaluation difference to improve quiet move ordering (~9 Elo)
740740
if (((ss - 1)->currentMove).is_ok() && !(ss - 1)->inCheck && !priorCapture)
741741
{
742-
int bonus = std::clamp(-12 * int((ss - 1)->staticEval + ss->staticEval), -1749, 1584);
742+
int bonus = std::clamp(-11 * int((ss - 1)->staticEval + ss->staticEval), -1729, 1517);
743743
bonus = bonus > 0 ? 2 * bonus : bonus / 2;
744744
thisThread->mainHistory[~us][((ss - 1)->currentMove).from_to()] << bonus;
745745
if (type_of(pos.piece_on(prevSq)) != PAWN && ((ss - 1)->currentMove).type_of() != PROMOTION)
@@ -762,7 +762,7 @@ Value Search::Worker::search(
762762
// If eval is really low check with qsearch if it can exceed alpha, if it can't,
763763
// return a fail low.
764764
// Adjust razor margin according to cutoffCnt. (~1 Elo)
765-
if (eval < alpha - 473 - (308 - 138 * ((ss + 1)->cutoffCnt > 3)) * depth * depth)
765+
if (eval < alpha - 474 - (326 - 139 * ((ss + 1)->cutoffCnt > 3)) * depth * depth)
766766
{
767767
value = qsearch<NonPV>(pos, ss, alpha - 1, alpha);
768768
if (value < alpha)
@@ -773,21 +773,21 @@ Value Search::Worker::search(
773773
// The depth condition is important for mate finding.
774774
if (!ss->ttPv && depth < 11
775775
&& eval - futility_margin(depth, cutNode && !ss->ttHit, improving, opponentWorsening)
776-
- (ss - 1)->statScore / 258
776+
- (ss - 1)->statScore / 252
777777
>= beta
778778
&& eval >= beta && eval < VALUE_TB_WIN_IN_MAX_PLY && (!ttMove || ttCapture))
779779
return beta > VALUE_TB_LOSS_IN_MAX_PLY ? (eval + beta) / 2 : eval;
780780

781781
// Step 9. Null move search with verification search (~35 Elo)
782-
if (!PvNode && (ss - 1)->currentMove != Move::null() && (ss - 1)->statScore < 16079
783-
&& eval >= beta && ss->staticEval >= beta - 21 * depth + 324 && !excludedMove
782+
if (!PvNode && (ss - 1)->currentMove != Move::null() && (ss - 1)->statScore < 15246
783+
&& eval >= beta && ss->staticEval >= beta - 21 * depth + 366 && !excludedMove
784784
&& pos.non_pawn_material(us) && ss->ply >= thisThread->nmpMinPly
785785
&& beta > VALUE_TB_LOSS_IN_MAX_PLY)
786786
{
787787
assert(eval - beta >= 0);
788788

789789
// Null move dynamic reduction based on depth and eval
790-
Depth R = std::min(int(eval - beta) / 144, 6) + depth / 3 + 5;
790+
Depth R = std::min(int(eval - beta) / 152, 6) + depth / 3 + 5;
791791

792792
ss->currentMove = Move::null();
793793
ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
@@ -835,7 +835,7 @@ Value Search::Worker::search(
835835
// Step 11. ProbCut (~10 Elo)
836836
// If we have a good enough capture (or queen promotion) and a reduced search returns a value
837837
// much above beta, we can (almost) safely prune the previous move.
838-
probCutBeta = beta + 177 - 65 * improving;
838+
probCutBeta = beta + 176 - 65 * improving;
839839
if (
840840
!PvNode && depth > 3
841841
&& std::abs(beta) < VALUE_TB_WIN_IN_MAX_PLY
@@ -891,7 +891,7 @@ Value Search::Worker::search(
891891
moves_loop: // When in check, search starts here
892892

893893
// Step 12. A small Probcut idea, when we are in check (~4 Elo)
894-
probCutBeta = beta + 428;
894+
probCutBeta = beta + 440;
895895
if (ss->inCheck && !PvNode && ttCapture && (tte->bound() & BOUND_LOWER)
896896
&& tte->depth() >= depth - 4 && ttValue >= probCutBeta
897897
&& std::abs(ttValue) < VALUE_TB_WIN_IN_MAX_PLY && std::abs(beta) < VALUE_TB_WIN_IN_MAX_PLY)
@@ -975,15 +975,15 @@ Value Search::Worker::search(
975975
// Futility pruning for captures (~2 Elo)
976976
if (!givesCheck && lmrDepth < 7 && !ss->inCheck)
977977
{
978-
Value futilityValue = ss->staticEval + 305 + 272 * lmrDepth
978+
Value futilityValue = ss->staticEval + 276 + 256 * lmrDepth
979979
+ PieceValue[capturedPiece] + captHist / 7;
980980
if (futilityValue <= alpha)
981981
continue;
982982
}
983983

984984
// SEE based pruning for captures and checks (~11 Elo)
985-
int seeHist = std::clamp(captHist / 32, -185 * depth, 182 * depth);
986-
if (!pos.see_ge(move, -176 * depth - seeHist))
985+
int seeHist = std::clamp(captHist / 32, -177 * depth, 175 * depth);
986+
if (!pos.see_ge(move, -183 * depth - seeHist))
987987
continue;
988988
}
989989
else
@@ -994,18 +994,18 @@ Value Search::Worker::search(
994994
+ thisThread->pawnHistory[pawn_structure_index(pos)][movedPiece][move.to_sq()];
995995

996996
// Continuation history based pruning (~2 Elo)
997-
if (lmrDepth < 6 && history < -4360 * depth)
997+
if (lmrDepth < 6 && history < -4076 * depth)
998998
continue;
999999

10001000
history += 2 * thisThread->mainHistory[us][move.from_to()];
10011001

1002-
lmrDepth += history / 4507;
1002+
lmrDepth += history / 4401;
10031003

10041004
Value futilityValue =
1005-
ss->staticEval + (bestValue < ss->staticEval - 54 ? 142 : 55) + 132 * lmrDepth;
1005+
ss->staticEval + (bestValue < ss->staticEval - 53 ? 151 : 57) + 140 * lmrDepth;
10061006

10071007
// Futility pruning: parent node (~13 Elo)
1008-
if (!ss->inCheck && lmrDepth < 11 && futilityValue <= alpha)
1008+
if (!ss->inCheck && lmrDepth < 10 && futilityValue <= alpha)
10091009
{
10101010
if (bestValue <= futilityValue && std::abs(bestValue) < VALUE_TB_WIN_IN_MAX_PLY
10111011
&& futilityValue < VALUE_TB_WIN_IN_MAX_PLY)
@@ -1016,7 +1016,7 @@ Value Search::Worker::search(
10161016
lmrDepth = std::max(lmrDepth, 0);
10171017

10181018
// Prune moves with negative SEE (~4 Elo)
1019-
if (!pos.see_ge(move, -27 * lmrDepth * lmrDepth))
1019+
if (!pos.see_ge(move, -26 * lmrDepth * lmrDepth))
10201020
continue;
10211021
}
10221022
}
@@ -1036,11 +1036,11 @@ Value Search::Worker::search(
10361036
// so changing them requires tests at these types of time controls.
10371037
// Recursive singular search is avoided.
10381038
if (!rootNode && move == ttMove && !excludedMove
1039-
&& depth >= 4 - (thisThread->completedDepth > 33) + ss->ttPv
1039+
&& depth >= 4 - (thisThread->completedDepth > 35) + ss->ttPv
10401040
&& std::abs(ttValue) < VALUE_TB_WIN_IN_MAX_PLY && (tte->bound() & BOUND_LOWER)
10411041
&& tte->depth() >= depth - 3)
10421042
{
1043-
Value singularBeta = ttValue - (59 + 49 * (ss->ttPv && !PvNode)) * depth / 64;
1043+
Value singularBeta = ttValue - (57 + 50 * (ss->ttPv && !PvNode)) * depth / 64;
10441044
Depth singularDepth = newDepth / 2;
10451045

10461046
ss->excludedMove = move;
@@ -1050,14 +1050,14 @@ Value Search::Worker::search(
10501050

10511051
if (value < singularBeta)
10521052
{
1053-
int doubleMargin = 285 * PvNode - 228 * !ttCapture;
1053+
int doubleMargin = 298 * PvNode - 209 * !ttCapture;
10541054
int tripleMargin =
1055-
121 + 238 * PvNode - 259 * !ttCapture + 117 * (ss->ttPv || !ttCapture);
1055+
117 + 252 * PvNode - 270 * !ttCapture + 111 * (ss->ttPv || !ttCapture);
10561056

10571057
extension = 1 + (value < singularBeta - doubleMargin)
10581058
+ (value < singularBeta - tripleMargin);
10591059

1060-
depth += ((!PvNode) && (depth < 14));
1060+
depth += ((!PvNode) && (depth < 15));
10611061
}
10621062

10631063
// Multi-cut pruning
@@ -1092,7 +1092,7 @@ Value Search::Worker::search(
10921092
else if (PvNode && move == ttMove && move.to_sq() == prevSq
10931093
&& thisThread->captureHistory[movedPiece][move.to_sq()]
10941094
[type_of(pos.piece_on(move.to_sq()))]
1095-
> 4041)
1095+
> 3748)
10961096
extension = 1;
10971097
}
10981098

@@ -1143,10 +1143,10 @@ Value Search::Worker::search(
11431143

11441144
ss->statScore = 2 * thisThread->mainHistory[us][move.from_to()]
11451145
+ (*contHist[0])[movedPiece][move.to_sq()]
1146-
+ (*contHist[1])[movedPiece][move.to_sq()] - 5313;
1146+
+ (*contHist[1])[movedPiece][move.to_sq()] - 5266;
11471147

11481148
// Decrease/increase reduction for moves with a good/bad history (~8 Elo)
1149-
r -= ss->statScore / (16145 - std::min(depth, 15) * 102);
1149+
r -= ss->statScore / (14519 - std::min(depth, 15) * 103);
11501150

11511151
// Step 17. Late moves reduction / extension (LMR, ~117 Elo)
11521152
if (depth >= 2 && moveCount > 1 + rootNode)
@@ -1165,7 +1165,7 @@ Value Search::Worker::search(
11651165
{
11661166
// Adjust full-depth search based on LMR results - if the result
11671167
// was good enough search deeper, if it was bad enough search shallower.
1168-
const bool doDeeperSearch = value > (bestValue + 41 + 2 * newDepth); // (~1 Elo)
1168+
const bool doDeeperSearch = value > (bestValue + 40 + 2 * newDepth); // (~1 Elo)
11691169
const bool doShallowerSearch = value < bestValue + newDepth; // (~2 Elo)
11701170

11711171
newDepth += doDeeperSearch - doShallowerSearch;
@@ -1326,9 +1326,9 @@ Value Search::Worker::search(
13261326
// Bonus for prior countermove that caused the fail low
13271327
else if (!priorCapture && prevSq != SQ_NONE)
13281328
{
1329-
int bonus = (depth > 4) + (depth > 5) + (PvNode || cutNode) + ((ss - 1)->statScore < -14323)
1330-
+ ((ss - 1)->moveCount > 10) + (!ss->inCheck && bestValue <= ss->staticEval - 120)
1331-
+ (!(ss - 1)->inCheck && bestValue <= -(ss - 1)->staticEval - 76);
1329+
int bonus = (depth > 4) + (depth > 5) + (PvNode || cutNode) + ((ss - 1)->statScore < -13241)
1330+
+ ((ss - 1)->moveCount > 10) + (!ss->inCheck && bestValue <= ss->staticEval - 127)
1331+
+ (!(ss - 1)->inCheck && bestValue <= -(ss - 1)->staticEval - 74);
13321332
update_continuation_histories(ss - 1, pos.piece_on(prevSq), prevSq,
13331333
stat_bonus(depth) * bonus);
13341334
thisThread->mainHistory[~us][((ss - 1)->currentMove).from_to()]
@@ -1494,7 +1494,7 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
14941494
if (bestValue > alpha)
14951495
alpha = bestValue;
14961496

1497-
futilityBase = ss->staticEval + 259;
1497+
futilityBase = ss->staticEval + 264;
14981498
}
14991499

15001500
const PieceToHistory* contHist[] = {(ss - 1)->continuationHistory,
@@ -1566,11 +1566,11 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
15661566
+ (*contHist[1])[pos.moved_piece(move)][move.to_sq()]
15671567
+ thisThread->pawnHistory[pawn_structure_index(pos)][pos.moved_piece(move)]
15681568
[move.to_sq()]
1569-
<= 4057)
1569+
<= 4348)
15701570
continue;
15711571

15721572
// Do not search moves with bad enough SEE values (~5 Elo)
1573-
if (!pos.see_ge(move, -68))
1573+
if (!pos.see_ge(move, -63))
15741574
continue;
15751575
}
15761576

@@ -1636,7 +1636,7 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
16361636

16371637
Depth Search::Worker::reduction(bool i, Depth d, int mn, int delta) {
16381638
int reductionScale = reductions[d] * reductions[mn];
1639-
return (reductionScale + 1284 - delta * 755 / rootDelta) / 1024 + (!i && reductionScale > 1133);
1639+
return (reductionScale + 1147 - delta * 755 / rootDelta) / 1024 + (!i && reductionScale > 1125);
16401640
}
16411641

16421642
// elapsed() returns the time elapsed since the search started. If the

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